Hi ASIM_BHATTI,
Most of the information you are seeking with the PCI-6225 can be found in the 6225 Specifications page or the M Series User Manual. Here is some specification information answering the questions you had.
1) As this DAQ (NI PCI-6225 ) is using single ADC for multiple channels at input, what is the time delay from first channel to the last channel?
This knowledgebase describes how to calculate the maximum and minimum interchannel delays associated with you DAQ device. This should help determine how much time it would take from measuring the first to last channel.
2) What is the sampling rate of individual input channel: 250 kS/s or (250/80) kS/s ?
Looking at the Specifications manual linked above on page1, the sampling rate is 250 kS/s multichannel aggregate meaning that if you were using all 80 channels single ended, each channel would have a sampling rate of (250/80) kS/s.
3) I want to develop my own application software for real time data reading and writing from DAQ in Microsoft Visual C++ or Borland C/C++. What are the essential software needed to be purchase for this development?
The PCI-6225 includes the NI-DAQmx driver which is the software package that allows you to communicate with the card. You would obviously need the software packages for the Microsoft Visual C++ (Microsoft Visual Studio 2005) or Borland C/C++. I would recommend using Microsoft Visual C++ because the knowledge and support is better with this software development system.
4) Can single channel input sampling rate be set different from 250kS/s e.g. 24kS/s?
The sampling rates for channels can be software selected. However, the sampling rates for each individual channel will be the same as other channels.
5) Can this DAQ measure voltage levels around +/- 10mV ? and what is voltage level of its internal noise floor?
This information can be figured out in the Specifications manual on page 4 in the AI Absolute Accuracy Table. +/- 10 mV is definitely within the readable range of the DAQ card. Noise considerations are also in this table.
6) 80 analog channels differential output (-20 mV to 20 mV range) traveling on about 100-200 m of twisted cables (AWG30 impedance approx 330 ohms) do we need an external voltage follower circuit?
First, I want to make sure that you understand that you can measure 80 analog input channels only if you are measuring single ended and 40 channels if you are measuring differential. Differential measurements would be done with floating sinal sources where you are concerned with not measuring the common mode noise. If you want to meausure 80 channels, you have to make sure that your signals are ground referenced singal sources. Refer to this developer zone document for more information on this topic.
The recommended cable for this device is included in the product page as the SHC-68 68 EPM cable. You should not need a voltage follower circuit if you use this cable. This knowledgebase describes additional information about this cable and you can relate it to the cable you need to use.
Hopefully this information has been helpful. Thanks!
Regards,
Vanessa L.
Applications Engineer
National Instruments
